Although the etiology of interstitial cystitis (IC) is unknown, there are several possible mechanisms by which the condition may mediate it symptomology- 1) A defect in the mucosal lining of the bladder (either in quantity or quality) would allow penetration of substances from the urine into the underlying tissue. These substances may produce inflammation and irritation to the underlying smooth muscle thus producing the IC symptoms. 2) An auto-immune response of the body against bladder tissue would produce antibladder antibodies that may result in inflammation of the bladder and produce the IC symptoms. 3) The presence of specific contractile or irritating substances in the urine could produce the IC symptomatology if it could gain access to the underlying muscle layer. 4) A combination of any or all of above. This proposal approaches the problem from several directions: 1) Through the detailed immuno-histological and electron- microscopic evaluation of biopsies taken from confirmed and suspected IC patients, we propose to establish histological criteria for the diagnosis of IC in its early stages. 2) A study of the antibacterial adherence properties of the normal and IC urinary bladder (in humans) 3) Determination and identification of contractile substances in urine form IC patients as opposed to control urine 4) Creation of an IC animal model by A) studying the effect of the application of irritating agents on the bladder mucosa B) Induction of anti-bladder antibodies by injecting experimental animals with extracts of urinary bladder. Only though both an understanding of the etiology of interstitial cystitis, and the ability to diagnose the disease in its early stages can we hope to develop effective therapties for this condition.